A hook fastener with a spring closure is commonly used for engaging a ring or a fitting on a bag, camera, or the like, for attaching a belt. By releasably fastening the belt in this way, a bag may be provided, for instance, with a detachable shoulder strap or carry handle. A common hook fastener for this application has a sliding closure urged by a spring to close the mouth of the hook.
To provide some degree of security when leaving a bag briefly unattended the user may loop a releasably fastened shoulder strap about a piece of furniture, or the like. This simple technique can be performed quickly and without drawing attention and this has been found sufficient to defeat casual theft. Of course for greater security the end of the strap could be fixed to the bag by a lock, however a lock would add considerable cost and weight to the fastener. It will be understood, therefore, that there is a need for a hook fastener for such an application that is able to provide improved deterrence of casual theft, without substantially increasing the cost of the fastener. It is an object of the present invention to overcome to address this need or, more generally, to provide an improved hook fastener.